This invention relates to a carrier member for use on a drag chain conveyor for loose articles.
Drag chain conveyors are frequently used for the conveyance of loose articles, for example bottles in bottle washing machines. Such drag chain conveyors normally comprise two conveyor chains which are spaced apart and parallel to each other. The conveyor chains are actuated to move in the same direction. The space defined between the two conveyor chains is the conveying channel. Associated with some or all of the links on each of the conveyor chains is a carrier member. These carrier members are disposed such that they extend inwardly into the conveying channel so that loose articles in this channel are engaged by such carriers and moved thereby.
Each carrier member usually consists of a gripper member for gripping the loose articles in the conveying channel, and a holder connectable to a chain link as well as to the gripper member.
In drag chain conveyors of this kind, provision is frequently made for lubricating the chain guide with oil. As a consequence, the gripper members and particularly those parts of the gripper members near the chain, are often in an oily atmosphere during operation. Moreover, if the drag chain conveyor is operated in conjunction with a bottle washing machine, washing liquid may also be splashed onto the gripper members. Additionally, in the beverages industry, the drag chain conveyors are regularly cleaned with superheated high-pressure steam. All these factors directly affect the life of the gripper members. Thus it is important that a suitable resilient material is chosen for the gripper members so that a maximum life therefor is obtained.
Yet a further problem in relation to the gripper members is the maintenance of the adhesive force between the gripper members and the articles to be conveyed. In the case of bottle-washing, there is a danger that the bottles may escape from the grip of the gripper members if at a point of deflection of the conveyor the longitudinal axes of the bottles (which are gripped at their sides) lie in the direction of the centrifugal force applied to the bottles. This point of deflection may occur at a bend in the conveyor chains or at a joinder point between conveyor chains or between a conveyor chain and another object.
In order to increase the gripping properties of the gripper members, prior art carrier members have been provided wherein the gripping surface has a number of sharp-edged ribs with smooth surfaces therebetween. While this may be adequate for use in a dry atmosphere, the adhesive power of these grippers is however significantly reduced in a wet atmosphere since the ribs do not prevent the formation of a film of liquid on the article and further assist the retention of the film. In addition, ribs have the disadvantage that when they act on, for example a glass article, there is a minimal surface area contact between the glass article and the gripper member (i.e. at the rib edges only) so that the adhesive power is considerably reduced. Prior art devices are disclosed in U.S. Pat. Nos. 2,734,621, 2,297,295, 2,297,296 and Italian Pat. No. 721573.
U.S. Pat. No. 2,734,621 teaches the moving of bottles in an upright position. This movement is achieved by squeezing the bottles between two so-called flexible chains. These chains comprise metal plates flexibly joined by links and lined with a rubber lining. The effectiveness of the movement of the bottles within the conveyor depends to a large extent upon whether there is sufficient contact between the rubber lining and a very small part of the bottle surface (essentially a point contact). To facilitate proper contact, a plurality of complicated spring assemblies are necessary.
U.S. Pat. Nos. 2,297,295 and 2,297,296 disclose carrier systems comprised of an endless rubber hose that defines in its surface a number of regularly spaced intervals having horizontally disposed axes. The carrier transports items by making a first point contact and a second vertically disposed area contact. The effectiveness of the movement of the items depends upon the orientation of the major axis of the items being carried for sufficient contact between the carrier and the item.
Italian Pat. No. 721573 discloses a carrying device which uses grippers that consist of a metallic plate upon which trapezoidal-shaped rubber pieces are mounted. These rubber pieces are somewhat stiff and do not yield to the items that they carry.
It is an object of the present invention to provide an improved carrier member adapted to efficiently grip and transport objects.